Method of joining a beryllium workpiece to light metals

ABSTRACT

The joining of beryllium to light metals, such as magnesium and aluminum is performed according to the following method. The joining method according to this invention thus comprises the steps: A. DIPPING THE SOLID BERYLLIUM WORKPIECE IN A MOLTEN BATH OF COPPER OR COPPER ALLOY TO FORM THE DESIRED BERYLLIUM COPPER ALLOY ON THE SURFACE OF THE WORKPIECE; B. DIPPING SAID BERYLLIUM - COPPER ALLOY TREATED WORKPIECE IN A MOLTEN BATH OF ALUMINUM OR ALUMINUM ALLOY TO FORM THE BERYLLIUM-COPPER-ALUMINUM ALLOY ON THE SURFACE THEREOF; C. SETTING SAID SOLID WORKPIECE ALLOY INTO A MOLD; AND D. POURING A MOITEN LIGHT METAL INTO THE MOLD BEFORE THE SAID BERYLLIUM-COPPER-ALUMINUM ALLOY LAYER ON THE SURFACE OF SAID WORKPIECE IS SOLIDIFIED, THEREBY TO JOIN BERYLLIUM TO ALUMINUM OR ALUMINUM ALLOY CASTINGS OR TO JOIN BERYLLIUM TO MAGNESIUM CASTINGS.

United States Patent [1 1 Niimi et al.

[ Oct. 15,1974

[ METHOD OF JOINING A BERYLLIUM WORKPIECE TO LIGHT METALS [76] lnventors: ltaru Niimi, 4-1205, Aza-Obasama,

Ohaza-Takebari, ltaka-cho, Chikusa-ku, Nagoya-shi; Kametaro Hashimoto, 29, Takami-cho, S-chome, Toyota-shi; Yasuhisa Kaneko, 10, Toyota-cho, Toyota-shi; Yoshiro Komiyama, 48, Heiwa-cho 4-chome, Toyota-shi; Kunihiko Hashimoto, 14, Miyuki-hon-machi 6-chome, Toyota-shi, all of Aichi-ken, Japan [22] Filed: May 25, 1973 [21] Appl. No.: 360,645

Related US. Application Data [63] Continuation-in-part of Ser. No. 130,257, April 1,

1971, abandoned.

[52] US. Cl 164/75, 29/194, 29/504, 29/5273, 75/150, 117/131, 164/100 [51] Int. Cl B22d 19/04 [58] Field of Search 29/504, 527.3, 527.5, 191, 29/1914, 194; 117/71 M, 131; 75/150; 164/75, 100, 101

[56] References Cited UNITED STATES PATENTS 929,778 8/1909 Monnot 164/75 X 2,100,257 11/1937 Larson 3,378,356 4/1968 Larsen et al. 3,609,855 10/1971 Schmidt 3,687,737 8/1972 Krock et al. 29/5275 X FOREIGN PATENTS OR APPLICATIONS 788,239 12/1957 Great Britain 75/150 OTHER PUBLICATIONS Alien Property Custodian S/N 248,647 Published July 13, 1943.

Alien Property Custodian S/N 265,607 Published July 13, 1943.

Primary Examiner-Charles W. Lanham Assistant Examiner-D. C. Reiley, lll Attorney, Agent, or FirmMcGlew. and Tuttle 5 7 ABSTRACT d. pouring a moiten light metal into the mold before the said beryllium-copper-aluminum alloy layer on the surface of said workpiece is solidified, thereby to join beryllium to aluminum or aluminum alloy castings or to join beryllium to magnesium castings.

6 Claims, 3 Drawing Figures PATENIEDOU 5 m4 SHEET 10F 3 muzmmmmmm FIG.

m m fiszxm N mdsaxm m m l a m w Ikwzmmhm 5522.

PAIENIEMM H 3.841.386

SHEET 2 OF 3 FIG. 2

Example I Example 3 Example 2 Reference o Aluminium Alloy b Be-Al alloy c Beryllium d Mixture PAIENIEMM 3.841.386

SHEET 3 UP 3 FIG. 3

= '\BERYLLIUM ALUMINIUM ALLOY METHOD OF JOINING A BERYLLIUM WORKPIECE TO LIGHT METALS CROSS-REFERENCE TO PRIOR APPLICATION This application is a continuation-in-part of copending Application Serial No. 130,257 filed on April I, 1971 for METAL JOINING METHOD", now abandoned.

FIELD AND BACKGROUND OF THE INVENTION This invention relates to a method of joining a solid beryllium workpiece to light metals, especially, to light metal castings, such as castings of aluminum, aluminum alloys or magnesium. Briefly stated, this invention resides in performing the joining of the beryllium workpiece to the above-mentioned light metal castings by way of a medium such as copper or copper alloy which metallographically holds said two metals firmly together on solidification.

Hitherto, light metal castings such as aluminum and magnesium castings have been expected to offer a diversity of applications as they are advantageous in saving weight of structural metals. However, the strength of such castings at high temperatures is not so satisfactory. Therefore, the addition of beryllium having many excellent properties at high temperatures to such castings has been proposed as a means of improving strength and properties of such castings. Beryllium is,

however, difficult to form or machine, and especially difficult to cast into intricate castings. Moreover, another disadvantage of beryllium is its higher cost. Furthermore, beryllium is difficult to bond with light metals such as aluminum or magnesium on solidification, and therefore produces no compound. Thus, even if beryllium is directly joined to aluminum or magnesium, the resultant joint is nothing but a mere mixed layer, and therefore, the joining strength thereof is not so high.

In view of the foregoing, it is an object of this invention to provide a method of joining a solid beryllium workpiece to aluminum, aluminum alloys or magnesium-base light metal castings so that practically useful structural metals having improved joining strength can be produced.

SUMMARY OF THE INVENTION This invention is based on the discovery that beryllium can be metallographically bonded with copper, that copper can be so bonded with aluminum and that aluminum can be so bonded with magnesium. The joining method according to this invention thus comprises the steps:

a. dipping the solid beryllium workpiece in a molten bath of copper or copper alloy to form the desired beryllium copper alloy on the surface of the workpiece;

b. dipping said beryllium copper alloy treated workpiece in a molten bath of aluminum or aluminum alloy to form the beryllium-copper-aluminum alloy on the surface thereof;

c. setting said solid workpiece alloy into a mold; and

d. pouring a molten light metal into the mold before the said beryllium-copper-aluminum alloy on the surface of said workpiece is solidified, thereby to join beryllium to aluminum or aluminum alloy castings or to join beryllium to magnesium castings.

According to the method of this invention, the solid beryllium workpiece is closely joined with light metal castings by way of copper or copper alloy and a strong joint is obtained, irrespective of uneveness on the joint surface. Thus, this invention is capable of attaining high joining strength and is greatly useful in reducing the weight of structural metals.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

FIG. 1 is a graph illustrating the tensile strength test results on the joints in five examples where beryllium is joined to light metal castings according to the method of this invention, as well as in a reference example where beryllium is joined to aluminum alloy casting according to the conventional techniques;

FIG. 2 is a microscopic structure diagram of the joints in three of said five examples and the reference example; and

FIG. 3 is a photographic representation of a piston made according to the invention.

GENERAL DESCRIPTION OF PREFERRED EMBODIMENTS As a preparatory step, the foreign matter on the surface of the solid beryllium workpiece is removed by a suitable treatment. The foreign matter means dust, dirt, oil particles or the like deposited on the surface of a beryllium workpiece. The foreign matter, which adversely affects formation of Be-Cu alloy on the surface of the beryllium workpiece may be removed either by washing with trichlorethylene, alcohol and the like, or by shot blast with fine steel balls or glass particles. Then, beryllium is dipped in a molten bath of copper. In another embodiment, copper alloy, such as Cu-Si or the like, is also used. The dipping is carried out for a suitable period of time, for example, about three minutes until the copper is metallographically bonded to the surface of a solid beryllium workpiece to form the beryllium-copper alloy layer on the surface. Then, said beryllium-copper alloy surface of the workpiece is quickly dipped in a molten bath of aluminum. Also, any suitable aluminum alloy listed in JIS ACZB (Japanese Industrial Standard) is useful. This second dipping is carried out for a suitable period of time, for example, about 2 minutes until the aluminum is metallographically bonded to the surface of copper or the copper alloy to form the desired beryllium-copper-aluminum alloy layer. Then, said beryllium-copper-aluminum alloy is set into a predetermined type of mold. Before said aluminum is solidified, molten aluminum or aluminum alloy light metal is poured thereinto, thus joining beryllium to aluminum or aluminum alloy casting. In another embodiment, the said beryllium-copperaluminum alloy is set into a mold and then molten magnesium-base light metal is poured thereinto in the same manner as described above, thus joining beryllium to magnesium castings.

In this method, when cooling is performed under the condition where the beryllium-copper alloy is formed or under the condition where the beryllium-copperaluminum alloy layer is formed, the joining of beryllium to light metal castings is carried out in the same manner as described above by dipping them again in the molten bath of aluminum or aluminum alloy.

Illustrations of tensile strength are shown in the graph of FIG. 1. Shown in the graph of FIG. 1 are the examples I through 4 wherein beryllium is joined with aluminum alloy castings, according to this invention, the example wherein beryllium is joined with magnesium alloy casting according to this invention, and the reference example wherein beryllium is directly joined to aluminum alloy casting.

The following Table (seeattached page 8) shows conditions of preparing the metal joints according to the invention and according to a reference example without copper or copper alloy.

From the foregoing examples, the advantages of the invention are illustrated. For example, the strength of the joints made according to the invention is seen from the tensile strength test results shown in FIG. 1. It will also be seen from FIG. 1 that the tensile strength in the reference example employing the method other than the method according to the invention is 8.l kg/mm, while those in the examples 1 through 4 employing the method of this invention are more than two times as high as that in the reference example. Furthermore, it will be seen that the tensile strength in the example 5 is 1.5 times as high as that in the reference example. Referring to the microscopic structure diagram of the joint shown in FIG. 2, the structure in the reference example is of a coarse mixed layer, while those in the examples 1 through 3 employing the method of this invention are of a fine and complete alloy layer. In other words, the strength of joints obtained according to this invention is not only so much higher as to be remarkable, but the conventional joints are seen to be so inferior as to be regarded as practically useless. Furthermore, if the solid beryllium workpiece is dipped in a molten bath of Cu-Si, the joint strength becomes especially high. As shown in the Example 4, if the joining is carried out by performing cooling after in a molten bath of copper alloy 16% Cu. remainder: Si) at a temperature of 950C for two minutes to form the beryllium-copper alloy layer on a joint surface to which the aluminum alloy skirt portion is to be joined.

5 Immediately thereafter, the top member is dipped into a molten bath of aluminum alloy (3% Al, 6% Cu, remainder: Si) at a temperature of 750C, for two minutes to form beryllium-copper-aluminum alloy on the joint surface thereof. The thus formed top member is 10 set into a mold having a cavity for the skirt position and derstood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. Method of manufacturing a light metal alloy casting from a solid beryllium workpiece, comprising the steps:

a. dipping the solid beryllium workpiece in a molten bath of copper or copper alloy and forming a layer of beryllium-copper alloy on the surface of the solid beryllium workpiece;

b. dipping the so-obtained beryllium workpiece in a molten bath of aluminum or aluminum alloy and forming on said surface a layer of berylliumcopper-aluminum on the beryllium workpiece;

c. setting the said solid workpiece alloy into a mold,

3 5 and d. pouring a molten light metal into the mold before the said beryllium-copper-aluminum alloy on the surface of said workpiece is solidified, thereby to form a light metal casting together with said beryllium as one body.

2. Method of manufacturing a light metal alloy cast- COPPER ALLOY DlPPlNG ALUMINUM Aufov CONDITION DIPPING CONDITION CASTING REMARKS Alloy Temperature Time Alloy Temperature Time ALLOY "C min JIS min JIS EXAMPLE I Cu-l6% Si 950 3 AC2B 750 2 AC2B EXAMPLE 2 Cu-S0% Al 740 3 ACZB 750 2 AC2B EXAMPLE 3 Cu-l0% Mg 870 3 ACZB 750 2 ACZB EXAMPLE 4 Cu-l6% Si 950 3 AC2B 750 2 AC2B Cooled after dipping in aluminum bath and left for one day EXAMPLE 5 Cu-I6% Si 950 3 ACZB 750 2 MCl Reference ACZB 750 2 AC2B Example the forming of the beryllium-copper-aluminum alloy layer on the surface of the workpiece and then by dipping said workpiece in the molten bath of aluminum alloy again, a high strength is also obtained.

FIG. 3 illustrates a piston of reciprocating engines whose top portion is made of beryllium and whose skirt portion is made of aluminum alloy (9.5% by weight of Al, 3.5% Si, 1% Cu, 1% Mg, remainder: Ni). The piston is formed as follows: A solid top member made of beryllium is washed with trichlorethylene and then dipped ing, according to claim 1, wherein said light metal cast alloy is aluminum alloy.

3. Method of manufacturing a light metal alloy casting, according to claim 1, wherein said light metal cast 5. Method of manufacturing a light metal alloy cast- 6. Method of manufactu ng a light metal alloy casting, according to claim 1, wherein the molten bath of ing, according to claim 5, wherein the molten bath is copper is composed essentially of copper and silicon. about 16% copper b3 wfigllt and [:16 balance is silicon. 

1. METHOD OF MANUFACTURING A LIGHT METAL ALLOY CASTING FROM A SOLID BERYLLIUM WORKPIECE, COMPRISING THE STEPS: A. DIPPING THE SOLID BERYLLIUM WORKPIECE IN A MOLTEN BATH OF COPPER OR COPPER ALLOY AND FORMING A LAYER OF BERYLLIUMCOPPER ALLOY ON THE SURFACE OF THE SOLID BERYLLIUM WORKPIECE; B. DIPPING THE SO-OBTAINED BERYLLIUM WORKPIECE IN A MOLTEN BATH OF ALUMINUM OR ALUMINUM ALLOY AND FORMING ON SAID SURFACE A LAYER OF BERYLLIUM-COPPER-ALUMINUM ON THE BERYLLIUM WORKPIECE; C. SETTING THE SAID SOLID WORKPIECE ALLOY INTO A MOLD, AND D. POURING A MOLTEN LIGHT METAL INTO THE MOLD BEFORE THE SAID BERYLLIUM-COPPER-ALUMINUM ALLOY ON THE SURFACE OF SAID WORKPIECE IS SOLIDIFIED , , THEREBY TO FORM A LIGHT METAL CASTING TOGETHER WITH SAID BERYLLIUM AS ONE BODY.
 2. Method of manufacturing a light metal alloy casting, according to claim 1, wherein said light metal cast alloy is aluminum alloy.
 3. Method of manufacturing a light metal alloy casting, according to claim 1, wherein said light metal cast alloy is magnesium or aluminum alloy.
 4. Method of manufacturing a light metal alloy casting, according to claim 1, wherein said light metal cast alloy is selected from the group consisting of magnesium, aluminum, an alloy of magnesium, and an alloy of aluminum.
 5. Method of manufacturing a light metal alloy casting, according to claim 1, wherein the molten bath of copper is composed essentially of copper and silicon.
 6. Method of manufacturing a light metal alloy casting, according to claim 5, wherein the molten bath is about 16% copper by weight and the balance is silicon. 